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O. Janne Kjønaas

Research Professor

NIBIO Publications
NIBIO Projects

Division of Forest and Forest Resources

Forest and Climate

(+47) 940 59 995
janne.kjonaas@nibio.no

Place
Ås H8

Visiting address
Høgskoleveien 8, 1433 Ås

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Authors

Carl-Fredrik Johannesson H. Ilvesniemi O. Janne Kjønaas K.S. Larsen A. Lehtonen Jenni Nordén D. Paré Hanna Marika Silvennoinen J. Stendahl I. Stupak L. Vesterdal Lise Dalsgaard

Abstract

No abstract has been registered

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Authors

Rieke Lo Madsen Line Nybakken O. Janne Kjønaas Håvard Kauserud Johan Asplund

Abstract

Litter decomposition is coupled to carbon (C) sequestration through C release to the atmosphere, C transformation and nutrient release to the soil. We investigated if clear-cutting has long-term effects on this vital ecological process and consequently on C dynamics in boreal forests using twelve pairs of previously clear-cut and near-natural forests. Three litterbag experiments were conducted using (I) standardised spruce and bilberry litter, (II) melanised and non-melanised fungal necromass and (III) rooibos and green tea. We found weak and inconsistent effects of harvesting history, that did not depend on litter quality or mesofauna exclusion. Litter quality was more important in explaining net mass remaining for fungal necromass than for aboveground plant litter. Mesofauna exclusion had only marginal effects on initial litter decomposition. Results obtained with the highly standardised Tea Bag Index were not readily comparable to those of the plant litter or fungal necromass and we therefore question its use in this regional context. Further, we show that net mass or C remaining in the litterbags do not correlate consistently with in situ soil respiration. This finding is discussed in relation to previous measurements of soil C fluxes from the same system. In conclusion, we suggest that potential disturbances to the physical environment or the capacity of the decomposer community to facilitate litter decomposition are no longer clearly evident when clear-cut stands approach maturity.

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Authors

Rieke Lo Madsen Johan Asplund Line Nybakken Rebecca Biong O. Janne Kjønaas

Abstract

No abstract has been registered

Expand my NIBIO publications
Soil grid sample

Division of Forest and Forest Resources

Carbon sequestration in Norwegian spruce forest soils (CONSEQUENCE)


Norway has pledged to reduce its greenhouse gas emissions, and one of the strategies and ultimate goal is to increase the short and long-term sequestration of organic carbon in forest soil to enhance the carbon stock of soil organic carbon in forests. Generally, soil carbon makes up a large part of the carbon pool in boreal forests, and any disturbance-induced losses could be directly linked to the size of this pool. The decomposition of soil carbon is strongly influenced by temperature and moisture, both of which are impacted by climate change. Altering forest management strategies, such as extending rotation periods and clear-cutting methods, may either increase soil carbon storage or limit its loss.  In this new project we will examine soil carbon stock changes over an approximately twelve-year period in nine stands that represent three typical stages of Norwegian spruce forests: recently clear-cut stands, mature planted production forests, and older, naturally-established stands with no active management. We aim to identify the key drivers for soil carbon storage and stability, such as biological stability and temperature sensitivity, and factors affecting chemical and physical stability. We will quantify the standing tree biomass, the source of soil carbon from above and below ground tree litter and dead wood, the age of the soil carbon as well as the microbial diversity and abundance in these forest systems. The project aims to identify links between sol carbon changes, ecosystem carbon stocks, processes, microbial community structure, and diversity. Findings will be integrated with data from previous research projects to evaluate larger scale patterns in carbon stocks and dynamics. Furthermore, the project seeks to facilitate knowledge transfers between researchers, the forest industry, and stakeholders, and support the development of strategies for increased soil carbon sequestration in relation to management and climate change.

Active Updated: 29.10.2025
End: mar 2029
Start: apr 2025
My finished projects